Semimuffle forge furnace



June 5 1928.

W. M M.. HEPBURN SEMIMUFFLE FORGE FURNACE Filed April 30, 1927 nonto W/LL/AM M. HEFBURN 3313/1115 &umet I Patenta! June 5, 1928.

'UNITED STATES 15712363 PATEN'T OFFICE.

WILLIAI KOHEN HHBURN, QI" NEW YORK, Y., ASSIGNOR '1'0 SUBFACE GOE- BUSTIQN COMPANY, OI' NEW YORK, N. Y., A CORPORATION OI' NEW YOEK.

SEIMUFFLE FORGE FURNACE.

Application filed April 80,

This invention relates to improvements in' forge furnaces.

One of the ob'ects of the invention is to provide a forge urnace which shallbe par-- ticularly well adapted for heating one end of relatively elongated objects, for example,

steel' rods, one end only of which is required to be heated for the purpose of welding or shaping into one form or another as into bolt heads. Another object is to provide a forge. furnace of such construction that while initial or tpreliminary heating of the work may be e ected by causing burning gases to make intimate contact with the work, the final heating of the work may be done out of direct contact with the burn'- ing gases in order to avoid scaling or substantial oxidation of the work by the free oxygen or oxidizing gases whic may be 2 present in the burning gases.

Another object is to provide a forge furnace of such Construction that the initial heating of the work may be eflected not only by intimat'e contact with the burning gases but also indirectly by heat transmitted through the hearth or floor on which the work is supported. Another object is to provide a furnace of such construction that the work during it final heating may be sur- -ounded by any des'ired atmosphere as, for example, a reducing atmosphere irrespective of the atmosphere existing in'that part of the furnace where initial heating of the work is efl'ected.

The above and other objects of the invention will more fully appear from thefollow ing detailed description taken in connection with the accompanying drawing wherein the preferred form of the invention is shown.

In the drawings Fg.- 1 is a longitudinal vertical section through the improved furnace, the view repi resenting more or less diagrammaticall the main features of the furnace, the view eing taken on line 1-1 of Fig. 2;

Fig. 2 is in the main a horizontal section taken' on line 2-2 of Fig. 1, some of the parts being in plan, and

Fig. 3 is a vertical t'ansverse section taken on line 3-3 of Fig. 1, this view'a`s well as' Fig. 1 showing the work to be heated as consist ing of round bars. i

'As shown in the drawings, the improved 1927. Serial No. 187,?82.

forge furnace includes among other things, a man furnace chamber into which burning gases are introduced, there being rovided in' wardly over the muflle without entering the open end thereof. i

The furnace chamber is indicated at 10, the spent gas outlet at 12 and the burners at 14 of which a plurality are shown. In one side wall 16 of the furnace is a slot 18 through which the work pices 20 may -be introduced into and' removed from the furnace. Extending laterally fromside wall 16 in line with said slot 18 is the muflle, the roof of which is indicated at 22. This muflle does not extend the entire width of the furnace chamber. As shown in the drawin gs the outer side ,wall 24 of the muflle is spaced from the adjacent side wall 26 of the furnace, thus providing a passage or space 28 which communicates with the upper and lower portions of the furnace chamber. It may be stated at this point that the burners 14: are arranged 'to fire into the furnace chamber'both above and below the nuflle.

For convenience of description the muflie floor is designated by reference character 30. Extending 'forwardly from the muflle floor is a hearth 32 which, like' the muflle, itself, extends laterally from the furnae wall 16 and in line with the slot 18. On this hearth the work is placed for ipreliminary heating b direct contact with the heating gases. he hearth and muflle floor are shown as of the same width. The outer edge of the hearth may be provided with an upstanding ridge 34 in alignment with the muffle side wall 24 in order to prevent the work from being ext-ended too far into the furnace whereby the free forward progress of the work into the muflie would be prevented.

"The muflle floor 30 and its extension, i. e. the hearth- 32, may Conveniently be considered -as a heat-permeable.partition extending partially across the furnace chamber and the roof of the muflle as a beat-permeable shield.

The hearth 32 is preferably arranged to slope downwardly toward the muflle so .that round work ieces placed on the hearth may roll by gravty into the muflle as the work pieces are withdrawn from the latter. The muflle floor preferably also slopes in the same direction as the hearth.

The furnace roof preferably slopes downwardly toward that end of the hearth 32 farthest removed froin the muflle as indicated at 36, the fluc 12 communicating with the furnace chamber at the lowest portion of the root as indicated at 38. By sloping the roof in this manner the heatng gases are forced do wnwardly toward the hearth as will be readily appreciated and are therefore caused to make intimate contact with the work pieces resting thereon before they pass out-of the f rnace through the flue 12. The hearth or floor 32 is in spaced relation with respect to the floor or bottom of the 'furnace chamber as is also the floor 30 of the muflle and consequently there is formed a combustion chamber below said hearth and nufile floor. As already indicated, burning 'gases 'are introduced into the furnace below the muflle and consequently the hearth will be heated from below with the result that the work pieces resting thereon are heated indirectly from below as well as directly from above.

As already indicated the burning gases are introduced into the furnace adjacent the closed end of the muflle and flow forwardly over the muflle without any tendency to enter the open end thereof. The atmosphere within the muflie is therefore for all practical purposes a stagnant and inert atmosphere and for this reason final heating of the work may be efl'ected substantially free from scaling or oxidation such `as would tend to occur if the work were to be brought to its final temperature in the open atmosphere of the furnace above the hearth where more or less oxidizing gases exist.

I While there may be some infiltration of air through the side opening or slot 18 through which the work pieces' are removed from t he muflle, nevertheless such air will not tend here the work peces are hottest but' due to the draft 'created by -the flow of the heating gases through the furnace will rather tend to flow along the inside of the slot gas outlet 12.

toward the spent While the Construction of the, improved furnace s-such that no substantial oxida- 'tion or scaling' of the work will take place within the-muflle it is, oftentimes'desirable to provide an atmosphere in the .muflle which 'operation of the furnace. For 'exam le, it may be desirable to maintain a re ucing atmosphere in the muflle. In order that any desired atmospheric condition may be-maintained within the muflie I provide for the introduction into the muflle of such gases as will give the atmosphere desired. To this end I connect the closed end of the muflle with a conduit 40 which connects with a suitable ipe 42 outside of the furnace which pipe lea s to a source of supply of raw gas or any other suitable gas adapted for the intended purpose. It will be readily appreciated that raw or reducing gas introduced into the muflle through the closed end thereof will pass forward over the work and out through the open end of the muflie and finallyout through the spent gas outlet 12.

It should be noted that a furnace constructed in accordance with the present invention enables the greatest heat of the furnace to be localized where it is most desired, namely, along that portion of the muflie and hearth which extends farthest into the furnace chamber. This will be made more evident when it is pointed out that the burning gases introduced below the muflle must flow laterallythereof and into the space 28 and upwardly in order to pass out t rough the spent gas flue outlet 12. In the lower portion of the furnace chamber the 'circulation of the hot gases is more or less retarded 'by the furnace wall 16 and consequently relatively little heat is given up to' the immediately adjacent parts.

It will now be readily ap reciated that that part of the muflle cham r which extends tarthest into the furnace will be subjected to the active circulation of the fresh hot gases and consequently that end of the work which extends farthest into the muflle will become. the most highly heated by radiant heat from the muflle and furthermore that due to the manner in which the burning gases pass through the furnace, final heating in the muflle may be elfected without appreciable or objectionable oxidation of the work.

What is claimed is: v

1. The combination with a furnace chamber having an outlet for combustion gases at one end thereof, of an open-ended muflle therein having its open end facing the gas outlet end of said chamber whereby the heating gases tend to pass through said chamber without entel-ing the open end of the muflle, the floor of the muflle being extended-beyond its open end to .form a hearth on which the objects to be heatedmay be initially placed y for preliminary heating by the hot gases in said chamber, and independent firing means llO for introducing hot gases both above and below the muflle.

- 2. The combination with a furnace chamben havngjan outlet for combustion gases 3. The combination with a furnace cham-` ber having an outlet for combustion gases at one end thereof, of a muflie extending pa'tially across the fu'nace chamber from one side thereof and having an opening -in that end which facesthe gas outlet end of said chamber for the introduction of work to be heated, a hearth extending from the muflie floor longitudinaly of sad chamber for the initial reception of the work tobe heated in the muflie, said hearth-extending only artially across said chamber.`

4. 'Fhe combination with a furnace chamber havin an outlet for combustion gases at one en thereof, of an o n -ended muflie therein having its open en facing the gas outlet end of said chamber whereby the heating gasestend to pass through said chamber without entering the open end of the muflle, the floor of the muflie being extended beyond its open end to form a hearth on which theobjects to be heated in the muflle may be initially placed for preliminary heating by the' hot gases flowing through said chamber, and independent firng means for introducing hot gases into the furnace chamber both above and below the muflie. e

5. The combination with a furnace chamber having an outlet for' combustion gases at one end thereof, of a muflie extending partially across the furnace chamber from one side thereof and having aIr openin in that end which faces the gas outlet en of said chamber for the 'introduction of work to be heated, a hearth extending from the muflie floor longitudinally of said chamber for the reception of objects -to be -preliminarily heated before being passed nto the muflie for final heating, the furnace wall from which the muflle and hearth` extends being rovided with an elongated opening ex tendng lengthwise of the muflle floor and hearth whereby those p ortions of the objects not required to be heated may extend outwardl oj ,the furnace. E

6. Iii a furnace, the. combination of-a combustion chamber having at -one end thereof an outlet for combustion gases, a heat fper; meable partition extendin'g lengthwise o the chamber intermediate the top and bottom thereof and of a width les than\ the width of said chamber wherebyf the""`pp`er and lower portions of said chamber are in free,

communication with each other, means for introducing combustible gases into said chamber, a heat permeable shield overlyin a substantial portion of said artition, sai

shield starting from that en of the partition most' remote from the outlet for the combustion gases and terminating intermediate the ends of saidpartition, said partition serving' as a su port for the objects to be heated and said s eld serving to prevent combustion ases from making direct contact with t e objects therebelow, and a passage communicating with the. upper side of said artition to permit handling of the ob'ects t ereon from outside of' the furnace.

. In a furmce, the combination of a combustion chamber having at one end thereof an outlet for combustion gases, a heat permeable partition extending lengthwise of the chamber intermediate the" top and bottom thereof and of a width less than the width of said chamber whereby' the upper and' lower portions of said chamber' are in' free introducing combustible gases into said chamber, a heat permeable" shield' overlying a substantial portion of'said partition, said shield starting from'that 'endof the partition most remote from the outlet' for the u communication with each other,` means'for combustion gases and terminating interme- 4 'diate theends of said partition said' parti*- tion serving as a su rt for theobjectsto be heated and said s eld serving to prevent combustion gases from making direct contact with the objects therebelow, and a passage leading into the space below the shieid whereby a fluid medium may be introduced into sad space from a point exterior of the fnmace chamber. p 8. In a furnace, the combination of a combustion chamber, an open-ended muflie there- 4 in, a hearth extendin in alinement with the muflie floor for the nitia-l reception of the objects to be heated, means for supplying combustible gases adjacent the closed end of the muflie, a combustion-gas outlet adjacent that end of the hearth most distant 'from the muflle, a passage extending out of the furnace from the muflie through which passage a gaseous medium may beintroduced into the muflie,`and means through which work may be entered ;and removed from the furnace.

9. The combination with`a furnace chamber having an outlet for combustion gases 'at one end thereof, of n open-ended muflie therein having its open end facing the gas outlet end of said chamber whereby the heating gases tend to ass through said chamber without entering t e open end of the muflle, the floor of the mflle being extended beyond its open end to form a hearth on which the objects to be heated may be initially placed for preliminary heating by the hot 'gases in said chamber, said muflie and hearth being in vertically spaced relation with respect to thefloor and roof of said chamber.

10. In a furnace, the combination of a combustion chamber having at one end thereof an outlet for combustion gases, a heat permeabl'e partition extcnding lengthwise of the chamb'er intermediate between the top and bottom thereof and of a width less than the width of said chamber whereby the upper and lower portions of said chamber are in' free communication with each other, means for introducing combustible gases into said chamber, a heat permeable shield starting from that end of 'the partition most rcnote fronthe outlet of the combustion gases and tcrminating intermediate the ends' of sad partition, said partition serving as a support for the objects to be heated and said shield serving to prevent combustion the entry of' said heating gases into said passage.

12. In a furnace. the combination of an elongated chamber into which heating gases may be introduced for the heating of objects therewithin, a hearth along which the objects to be heated may be progressed for preliminary and final heating, said hearth eyond that. portion of its length necessary for the preliminary'heating of said objccts copstituting the floor of a relatively shallow passage into "which said objects enter for final heating, and means for introducing a gases into said fluid medium into said passage for flow through said passage in a direction 'counter to the incoming objects' 13. In a furnace, the combination of a heating zone wherein combustion gases may freely circulate. a hearth on which the objects to be heated may be exposed to direct contact with said gasses, a passage o en to said combustion gases and, into whic passage the objects enter for final heating, and means for i-ntroducing a fluid nedium into said passage to prevent the entry of said assage.-

14. A metho( of heating objccts which are progressed through a heating zone comprisng preliminary heating said objects to a pointbelow their final temperature in the presence of conbustion' gascs, conpleting the heating thereof in a passage tending to prevent said gases from contact-ing with said objects, and preventing the entry of said gases into the passage by passing a ga seous medium into the passage counter current to the movement of the objects into said passage.

15. A method of heating moving bjects comprising p'eliminarily heating the objects in a gaseous atmosphere consistingof products of combustion, 'completing the heating out of contact with' said gases by passing the objects into-a passage containinga gaseous medium which flows through the passage counter current to the incoming objects.

16. A method of heating steel objects comprising -initially passing the objects through a zone containing combustion gases and before the objects attain an oxidizing temperature passing them into a passage open to said gases and preventing the entry of said gases into said passage by causing' a gaseous medium to flow therethrough counter current to the incoming objects.

In testimony whereof, I aflix my signature, e WILLIAM MCMEEN HEPBURN. 

